Device for Biometrically Controlling a Face Surface

ABSTRACT

The invention relates to the devices for contactlessly measuring surface profiles and can be used for person identification in security systems. The inventive device for contactlessly controlling surface profile comprises a pulse illumination unit which is provided with a transparency and forms a transparency image on an object surface, and image recording unit and a computer. Said device also comprises a control unit which is connected to the image recording unit in the form of a TV camera with field interlacing, the pulse illumination unit and to the computer for synchronizing the illumination of the object surface by said pulse illumination unit with the TV camera field and for synchronizing the image processing by the computer with the TV interlacing. The transparency is embodied in the form of a line screen provided with an aperiodical different width band structure and a uniform transmission along each band, thereby making it possible to identify the sequence of the line screen images on the object surface.

FIELD OF ENGINEERING THE INVENTION RELATES TO

The invention relates to the devices for measuring surface contours and can be used for person identification in security systems.

STATE OF THE ART

A device for contactless control of the surface profile of objects is known, WO 00/70303 of Nov. 23, 2000, comprising of a pulse illumination unit provided with a pulse light source and a transparency, which forms a transparency image on an object surface, and an image recording unit.

The disadvantage of this device is that it is unpractical for biometrical control of a face profile, since it assumes arbitrary face orientation, which requires association of the face contour points with its image and complicates biometrical control of the face surface.

A device for biometrical control of a face surface is known, WO 02/09038 of Jan. 31, 2002, comprising a TV camera (image recording unit), a unit for displaying face position and a computer.

The disadvantage of this device is the low accuracy of measuring the position of the points on the face surface due to the fact that coordinates of these points are determined in plane only and not spatially, as well as the low operation rate of conducting a biometrical control, caused by the necessity of performing manual operations.

INVENTION DISCLOSURE

The invention aims at providing efficient biometric control of a face surface.

A technical result of utilization of this invention is an increase in control efficiency and accuracy in determining biometric face characteristics.

Described technical result is achieved by means of a device for biometrically controlling a face surface, which comprises a TV camera, a unit for displaying face position and a computer. This device additionally includes an illumination unit provided with a transparency and an objective lens for projecting transparency image on the face surface, which is arranged in such a way that optical axes of the objective lenses of the illumination unit and TV camera are disposed in one plane at an angle with respect to each other, while a unit for displaying face position is embodied and disposed in such a way that it makes it possible to display the symmetric face position with respect to the plane, formed by optical axes of the objective lenses of the illumination unit and TV camera.

The computer performs snap-association of the obtained contours of the face surface with the system of coordinates associated with a human face. For this purpose, the computer is provided with a capability to determine actual, asymmetrical face position with respect to the plane formed by the optical axes of the objective lenses of the illumination unit and a TV camera.

Objective lenses of the illumination unit and a TV camera can be positioned one under the other in such a way that their optical axes lie in a vertical plane and the unit for displaying a face position is positioned between them.

The transparency of the illumination unit can be realised in the form of a screen composed of parallel band segments and one band, which is transversal with respect to them along the axis of symmetry of the screen, and arranged in such a way that its transversal band is located in the vertical plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.

The unit for displaying the face position can be realized in the form of a planar mirror with a band and arranged in such a way that the band is located in the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.

The unit for displaying the face position can be realized in the form of a two-face mirror or in the form of several two-face mirrors, edges of which are located in the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.

The unit for displaying the face position can be realized in the form of a TV screen with a vertical marking defining the location of the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the schematic of the device for biometrical control of a face surface.

FIG. 2 schematically illustrates positioning of the device units as seen by a person at the time of biometrical control of his/her face.

FIGS. 3, 4 and 5 schematically show a combined mirror unit for displaying a face position.

BEST EMBODIMENT

According to the schematic shown in FIG. 1, the device includes an illumination block 1 provided with a transparency and an objective lenses for projecting the transparency image on the face surface, TV camera 2, computer 3 and a unit for displaying the face position 4.

Optical axes of the projecting objective lenses of the illumination unit 1 and TV camera 2 are disposed at an angle α with respect to each other.

The image of the transparency, distorted by the surface profile of the human face, is recorded by the TV camera and transmitted to the computer 3, which computes the height Z of the surface profile for a point with coordinates X,Y using the formula:

Z=ΔY/tan(α),

where ΔY is a measure of the transparency image band distortion. The computer determines characteristic points and fields of the face surface based on three coordinates.

The person, whose face is being analysed, orients his/her face as shown in FIG. 2 using a unit for displaying the face position 4, which can be realized in the form of a mirror or a TV screen with vertical marking, which allows orienting a nose along the marking or eyes—symmetrically with respect to the marking. The display unit can be realized in the form of a two-face mirror or a series of two-face mirrors (see FIGS. 3, 4 and 5), whose edges are located in the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.

Realization of a transparency of the illumination unit 1 in the form of a line screen with transversal band located in the plane, formed by the optical axes of the objective lenses of the illumination unit and TV camera, allows a person to orient his/her face symmetrically with respect to this transversal band by observing it in the unit for displaying the face position. In this case, the nose is positioned along the band.

The illumination unit and TV camera can operate outside of the visible part of the optical range.

The computer is realized with a capability to determine the actual asymmetrical position of the face with respect to the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera. 

1. A device for biometrically controlling a face surface, comprising a TV camera, a unit for displaying a face position, and a computer, wherein included additionally is an illumination unit provided with a transparency and an objective lens for projecting the transparency image on the face, which is located in such a way that the optical axes of the objective lenses of the illumination unit and those of the TV camera are disposed on the same plane at an angle with respect to each other, while the unit for displaying the face position is embodied and disposed in such a way that it makes it possible to display the symmetrical face position with respect to the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.
 2. A device according to claim 1, wherein the objective lenses of the illumination unit and TV camera are positioned one under the other, optical axes of their objective lenses are disposed in the vertical plane, and a unit for displaying the face position is located in between of them.
 3. A device according to claim 2, wherein a transparency of the illumination unit is embodied in the form of a screen composed of parallel band segments and one band, transversal to them along the axis of symmetry of the screen, and disposed in such a way that its transversal band is located in the vertical plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.
 4. A device according to claim 2, wherein a unit of displaying the face position is disposed in the form of two-face mirror or several two-face mirrors, whose edges are located in the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera.
 5. A device according to claim 2, wherein a unit of displaying the face position is disposed in the form of a TV screen with vertical marking defining the position of the plane formed by the optical axes of the objective lenses of the illumination unit and TV camera. 